Hello,
Duckdns (http://www.duckdns.org) is a service similar to no-ip, which offers up to 5 free forwarding addresses (you can set up 5 machines instead of only one like no-ip).
Installation is pretty simple (it's just a simple script to be run regularly in cron).

I have been using this service for years and it's very reliable and I think it could be a good addition to the software offerings of DietPi.

I think they didn't like your idea. But I use duckdns as well and would like to set it up on my RPi.
I'm pretty rubbish at scripts and stuff though, so if you would be willing to share yours I would be very grateful.
Thank you.